StartTask - Amazon Elastic Container Service


Starts a new task from the specified task definition on the specified container instance or instances.


On March 21, 2024, a change was made to resolve the task definition revision before authorization. When a task definition revision is not specified, authorization will occur using the latest revision of a task definition.

Starting April 15, 2023, AWS will not onboard new customers to Amazon Elastic Inference (EI), and will help current customers migrate their workloads to options that offer better price and performance. After April 15, 2023, new customers will not be able to launch instances with Amazon EI accelerators in Amazon SageMaker, Amazon ECS, or Amazon EC2. However, customers who have used Amazon EI at least once during the past 30-day period are considered current customers and will be able to continue using the service.

Alternatively, you can use RunTask to place tasks for you. For more information, see Scheduling Tasks in the Amazon Elastic Container Service Developer Guide.

You can attach Amazon EBS volumes to Amazon ECS tasks by configuring the volume when creating or updating a service. For more infomation, see Amazon EBS volumes in the Amazon Elastic Container Service Developer Guide.

Request Syntax

{ "cluster": "string", "containerInstances": [ "string" ], "enableECSManagedTags": boolean, "enableExecuteCommand": boolean, "group": "string", "networkConfiguration": { "awsvpcConfiguration": { "assignPublicIp": "string", "securityGroups": [ "string" ], "subnets": [ "string" ] } }, "overrides": { "containerOverrides": [ { "command": [ "string" ], "cpu": number, "environment": [ { "name": "string", "value": "string" } ], "environmentFiles": [ { "type": "string", "value": "string" } ], "memory": number, "memoryReservation": number, "name": "string", "resourceRequirements": [ { "type": "string", "value": "string" } ] } ], "cpu": "string", "ephemeralStorage": { "sizeInGiB": number }, "executionRoleArn": "string", "inferenceAcceleratorOverrides": [ { "deviceName": "string", "deviceType": "string" } ], "memory": "string", "taskRoleArn": "string" }, "propagateTags": "string", "referenceId": "string", "startedBy": "string", "tags": [ { "key": "string", "value": "string" } ], "taskDefinition": "string", "volumeConfigurations": [ { "managedEBSVolume": { "encrypted": boolean, "filesystemType": "string", "iops": number, "kmsKeyId": "string", "roleArn": "string", "sizeInGiB": number, "snapshotId": "string", "tagSpecifications": [ { "propagateTags": "string", "resourceType": "string", "tags": [ { "key": "string", "value": "string" } ] } ], "terminationPolicy": { "deleteOnTermination": boolean }, "throughput": number, "volumeType": "string" }, "name": "string" } ] }

Request Parameters

For information about the parameters that are common to all actions, see Common Parameters.

The request accepts the following data in JSON format.


The short name or full Amazon Resource Name (ARN) of the cluster where to start your task. If you do not specify a cluster, the default cluster is assumed.

Type: String

Required: No


The container instance IDs or full ARN entries for the container instances where you would like to place your task. You can specify up to 10 container instances.

Type: Array of strings

Required: Yes


Specifies whether to use Amazon ECS managed tags for the task. For more information, see Tagging Your Amazon ECS Resources in the Amazon Elastic Container Service Developer Guide.

Type: Boolean

Required: No


Whether or not the execute command functionality is turned on for the task. If true, this turns on the execute command functionality on all containers in the task.

Type: Boolean

Required: No


The name of the task group to associate with the task. The default value is the family name of the task definition (for example, family:my-family-name).

Type: String

Required: No


The VPC subnet and security group configuration for tasks that receive their own elastic network interface by using the awsvpc networking mode.

Type: NetworkConfiguration object

Required: No


A list of container overrides in JSON format that specify the name of a container in the specified task definition and the overrides it receives. You can override the default command for a container (that's specified in the task definition or Docker image) with a command override. You can also override existing environment variables (that are specified in the task definition or Docker image) on a container or add new environment variables to it with an environment override.


A total of 8192 characters are allowed for overrides. This limit includes the JSON formatting characters of the override structure.

Type: TaskOverride object

Required: No


Specifies whether to propagate the tags from the task definition or the service to the task. If no value is specified, the tags aren't propagated.

Type: String


Required: No


The reference ID to use for the task.

Type: String

Required: No


An optional tag specified when a task is started. For example, if you automatically trigger a task to run a batch process job, you could apply a unique identifier for that job to your task with the startedBy parameter. You can then identify which tasks belong to that job by filtering the results of a ListTasks call with the startedBy value. Up to 36 letters (uppercase and lowercase), numbers, hyphens (-), forward slash (/), and underscores (_) are allowed.

If a task is started by an Amazon ECS service, the startedBy parameter contains the deployment ID of the service that starts it.

Type: String

Required: No


The metadata that you apply to the task to help you categorize and organize them. Each tag consists of a key and an optional value, both of which you define.

The following basic restrictions apply to tags:

  • Maximum number of tags per resource - 50

  • For each resource, each tag key must be unique, and each tag key can have only one value.

  • Maximum key length - 128 Unicode characters in UTF-8

  • Maximum value length - 256 Unicode characters in UTF-8

  • If your tagging schema is used across multiple services and resources, remember that other services may have restrictions on allowed characters. Generally allowed characters are: letters, numbers, and spaces representable in UTF-8, and the following characters: + - = . _ : / @.

  • Tag keys and values are case-sensitive.

  • Do not use aws:, AWS:, or any upper or lowercase combination of such as a prefix for either keys or values as it is reserved for AWS use. You cannot edit or delete tag keys or values with this prefix. Tags with this prefix do not count against your tags per resource limit.

Type: Array of Tag objects

Array Members: Minimum number of 0 items. Maximum number of 50 items.

Required: No


The family and revision (family:revision) or full ARN of the task definition to start. If a revision isn't specified, the latest ACTIVE revision is used.

Type: String

Required: Yes


The details of the volume that was configuredAtLaunch. You can configure the size, volumeType, IOPS, throughput, snapshot and encryption in TaskManagedEBSVolumeConfiguration. The name of the volume must match the name from the task definition.

Type: Array of TaskVolumeConfiguration objects

Required: No

Response Syntax

{ "failures": [ { "arn": "string", "detail": "string", "reason": "string" } ], "tasks": [ { "attachments": [ { "details": [ { "name": "string", "value": "string" } ], "id": "string", "status": "string", "type": "string" } ], "attributes": [ { "name": "string", "targetId": "string", "targetType": "string", "value": "string" } ], "availabilityZone": "string", "capacityProviderName": "string", "clusterArn": "string", "connectivity": "string", "connectivityAt": number, "containerInstanceArn": "string", "containers": [ { "containerArn": "string", "cpu": "string", "exitCode": number, "gpuIds": [ "string" ], "healthStatus": "string", "image": "string", "imageDigest": "string", "lastStatus": "string", "managedAgents": [ { "lastStartedAt": number, "lastStatus": "string", "name": "string", "reason": "string" } ], "memory": "string", "memoryReservation": "string", "name": "string", "networkBindings": [ { "bindIP": "string", "containerPort": number, "containerPortRange": "string", "hostPort": number, "hostPortRange": "string", "protocol": "string" } ], "networkInterfaces": [ { "attachmentId": "string", "ipv6Address": "string", "privateIpv4Address": "string" } ], "reason": "string", "runtimeId": "string", "taskArn": "string" } ], "cpu": "string", "createdAt": number, "desiredStatus": "string", "enableExecuteCommand": boolean, "ephemeralStorage": { "sizeInGiB": number }, "executionStoppedAt": number, "fargateEphemeralStorage": { "kmsKeyId": "string", "sizeInGiB": number }, "group": "string", "healthStatus": "string", "inferenceAccelerators": [ { "deviceName": "string", "deviceType": "string" } ], "lastStatus": "string", "launchType": "string", "memory": "string", "overrides": { "containerOverrides": [ { "command": [ "string" ], "cpu": number, "environment": [ { "name": "string", "value": "string" } ], "environmentFiles": [ { "type": "string", "value": "string" } ], "memory": number, "memoryReservation": number, "name": "string", "resourceRequirements": [ { "type": "string", "value": "string" } ] } ], "cpu": "string", "ephemeralStorage": { "sizeInGiB": number }, "executionRoleArn": "string", "inferenceAcceleratorOverrides": [ { "deviceName": "string", "deviceType": "string" } ], "memory": "string", "taskRoleArn": "string" }, "platformFamily": "string", "platformVersion": "string", "pullStartedAt": number, "pullStoppedAt": number, "startedAt": number, "startedBy": "string", "stopCode": "string", "stoppedAt": number, "stoppedReason": "string", "stoppingAt": number, "tags": [ { "key": "string", "value": "string" } ], "taskArn": "string", "taskDefinitionArn": "string", "version": number } ] }

Response Elements

If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in JSON format by the service.


Any failures associated with the call.

Type: Array of Failure objects


A full description of the tasks that were started. Each task that was successfully placed on your container instances is described.

Type: Array of Task objects


For information about the errors that are common to all actions, see Common Errors.


These errors are usually caused by a client action. This client action might be using an action or resource on behalf of a user that doesn't have permissions to use the action or resource. Or, it might be specifying an identifier that isn't valid.

The following list includes additional causes for the error:

  • The RunTask could not be processed because you use managed scaling and there is a capacity error because the quota of tasks in the PROVISIONING per cluster has been reached. For information about the service quotas, see Amazon ECS service quotas.

HTTP Status Code: 400


The specified cluster wasn't found. You can view your available clusters with ListClusters. Amazon ECS clusters are Region specific.

HTTP Status Code: 400


The specified parameter isn't valid. Review the available parameters for the API request.

HTTP Status Code: 400


These errors are usually caused by a server issue.

HTTP Status Code: 500


The specified task isn't supported in this Region.

HTTP Status Code: 400


In the following example or examples, the Authorization header contents (AUTHPARAMS) must be replaced with an AWS Signature Version 4 signature. For more information, see Signature Version 4 Signing Process in the AWS General Reference.

You only need to learn how to sign HTTP requests if you intend to create them manually. When you use the AWS Command Line Interface or one of the AWS SDKs to make requests to AWS, these tools automatically sign the requests for you, with the access key that you specify when you configure the tools. When you use these tools, you don't have to sign requests yourself.


This example request starts the latest ACTIVE revision of the hello_world task definition family in the default cluster on the container instance with the ID 4c543eed-f83f-47da-b1d8-3d23f1da4c64.

Sample Request

POST / HTTP/1.1 Host: Accept-Encoding: identity Content-Length: 97 X-Amz-Target: AmazonEC2ContainerServiceV20141113.StartTask X-Amz-Date: 20161121T220032Z User-Agent: aws-cli/1.11.13 Python/2.7.12 Darwin/16.1.0 botocore/1.4.66 Content-Type: application/x-amz-json-1.1 Authorization: AUTHPARAMS { "containerInstances": [ "4c543eed-f83f-47da-b1d8-3d23f1da4c64" ], "taskDefinition": "hello_world" }

Sample Response

HTTP/1.1 200 OK Server: Server Date: Mon, 21 Nov 2016 22:00:32 GMT Content-Type: application/x-amz-json-1.1 Content-Length: 1025 Connection: keep-alive x-amzn-RequestId: 123a4b56-7c89-01d2-3ef4-example5678f { "failures": [], "tasks": [ { "clusterArn": "arn:aws:ecs:us-east-1:012345678910:cluster/default", "containerInstanceArn": "arn:aws:ecs:us-east-1:012345678910:container-instance/default/4c543eed-f83f-47da-b1d8-3d23f1da4c64", "containers": [ { "containerArn": "arn:aws:ecs:us-east-1:012345678910:container/e76594d4-27e1-4c74-98b5-46a6435eb769", "lastStatus": "PENDING", "name": "wordpress", "taskArn": "arn:aws:ecs:us-east-1:012345678910:task/default/fdf2c302-468c-4e55-b884-5331d816e7fb" }, { "containerArn": "arn:aws:ecs:us-east-1:012345678910:container/default/b19106ea-4fa8-4f1d-9767-96922c82b070", "lastStatus": "PENDING", "name": "mysql", "taskArn": "arn:aws:ecs:us-east-1:012345678910:task/default/fdf2c302-468c-4e55-b884-5331d816e7fb" } ], "createdAt": 1479765460.842, "desiredStatus": "RUNNING", "lastStatus": "PENDING", "overrides": { "containerOverrides": [ { "name": "wordpress" }, { "name": "mysql" } ] }, "taskArn": "arn:aws:ecs:us-east-1:012345678910:task/default/fdf2c302-468c-4e55-b884-5331d816e7fb", "taskDefinitionArn": "arn:aws:ecs:us-east-1:012345678910:task-definition/hello_world:6", "version": 1 } ] }

See Also

For more information about using this API in one of the language-specific AWS SDKs, see the following: